When installing, testing, maintaining, or tuning all ranges of fiber optic networks it is necessary to use various test sets. A test set ordinarily will include one or more fiber optic jumper cables for verifying the integrity of signal flow through various parts of the fiber optic circuit. The length of the fiber optic jumper cable depends on the distance that must be spanned by such cable.
A fiber optic jumper cable used for testing purposes in the field conventionally is accommodated for shipment in a transparent, flimsy, plastic storage bag. Conventionally, a jumper cable is wound about a radius of two inches or more to form a coil which is placed in the plastic bag without any additional protection against damage from externally applied forces, such as that resulting from being stepped on or struck by falling objects. The storage of a fiber optic cable in a flimsy plastic bag is undesirable because of the susceptibility to damage of such cable while accommodated in such bag.
A fiber optic jumper cable has certain known physical and optical characteristics, such as the cable diameter and its signal transmissivity attenuating properties. The attenuating properties usually are determined at about the time the cable is coiled without signal affecting bends for packaging, whereas the diameter of the cable determines the minimum radius about which the cable may be bent or wound to ensure against damaging the cable. These characteristics may be embraced by the term “minimum bending radius” which, as used herein, means the minimum radius about which a cable may be bent without subjecting the cable to physical damage or any appreciable loss of signal transmissivity.
When a field engineer extracts a coiled fiber optic jumper cable from the bag in which it is stored, it is common for the engineer to discard the plastic bag and manually uncoil and recoil the cable prior to and following its use. Manual uncoiling of the cable frequently causes the cable to become twisted or kinked, whereas manual recoiling of the cable subjects it to the possibility that it will be wound about a radius less than the minimum bending radius, thereby physically damaging the cable and adversely affect its ability to transmit an optical signal without undue attenuation.
In those instances in which the test set and a fiber optic jumper cable are shipped or stored in the same container, the cable is exposed to the possibility of damage by the test equipment itself.
The distance from the test set to the equipment under test varies in different testing environments. The current practice, therefore, requires the selection of a length of cable, which almost always is greater than the distance to be spanned, thereby resulting in excessive sagging of the cable between its ends and requiring the cable, after use, to be recoiled by hand resulting in uncertain bending radii and increasing the risk of damaging the cable.
A principal object of the invention is to provide apparatus which overcomes these disadvantages.